Fresh Water Fishery Viral Hemorrhagic Septicemia Virus (VHSV) Risk

Continuing our Risk Assessment Series...

The viral hemorrhagic septicemia virus (VHSV), which causes anemia and hemorrhaging in fish, first detected in the Great Lakes in June 2006, has now been identified in 23 species and is approaching epidemic proportions. This could have a devastating impact on sport fishing and aquaculture industries, not to mention our much smaller primitive and wilderness skills community. Fish biologists do not know how the disease is transmitted making it very difficult to prevent. There remains no way to vaccinate fish against this disease, and any measures to control its spread require people to apply procedures that existed prior to the discovery of vaccines, such as monitoring outbreaks and trying to isolate fish so they don't spread the disease.

Three new fish kills have occurred in 2007 in New York waters since the virus was identified in the Great Lakes Basin in 2005. In the St. Lawrence River, hundreds of thousands of round gobies have succumbed to the disease; gizzard shad die-offs from VHSV in Lake Ontario west of Rochester and in Dunkirk Harbor on Lake Erie also have been reported. Adding to concerns about the spread of the virus, walleye in Conesus Lake have tested positive for VHSV. Conesus is the westernmost Finger Lake and is the only New York Lake where VHSV has been found in a body of water other than the contiguous waters of the Great Lakes.

Other species from the Great Lakes Basin area that have tested positive by Cornell include bluegill, rock bass, black crappie, pumpkinseed, smallmouth and largemouth bass, muskellunge, northern pike, walleye, yellow perch, channel catfish, brown bullhead, white perch, white bass, emerald shiner, bluntnose minnow, freshwater drum, round goby, gizzard shad and burbot.

Risks: The Great Lakes VHSV is not related to the European or Japanese genotypes and poses no health threat to humans. However, as a general rule, people should avoid eating any fish (or game) that appears abnormal or behaves abnormally. Not all infected fish, however, exhibit symptoms. Some may be carriers, and visible signs of the disease may vary from species to species. The virus has been detected in Virginia, Maryland, Pennsylvania, District of Columbia or West Virginia water sheds.

Cornell University Cronicle OnLine article by Krishna Ramanujan.